Known in the art is a SAW device having a longitudinally-coupled multi-mode SAW filter in which a plurality of IDT electrodes are arranged in a propagation direction of the SAW (for example, Patent Literature 1). In Patent Literature 1, in order to improve the durability against electrostatic discharge (ESD), each IDT electrode is formed as a so-called serially divided type IDT electrode. That is, in each IDT electrode in PLT 1, between a first comb-shaped electrode which is arranged on one side in a direction orthogonal to the propagation direction of the SAW and connected to a signal line and a second comb-shaped electrode which is arranged on the other side in the orthogonal direction and connected to the ground, a third comb-shaped electrode in an electrically floating state is arranged.
However, if each IDT electrode is formed as a serially divided type as in Patent Literature 1, the SAW device ends up becoming larger in size in the direction orthogonal to the propagation direction.
Accordingly, desirably an acoustic wave device capable of improving the ESD durability without an increase in size is provided.